Forklift trucks are industrial vehicles and may be of various wheeled types. Forklift trucks may be used for cargo loading and unloading, stacking and short distance transportation operations. The international standards organization ISO/TC110 refers to them as industrial vehicles, and forklift trucks commonly are used to transport large objects, usually using a motor that includes a fueled engine or a battery drive.
A three pivot forklift truck is a forklift truck that the entire weight of the forklift truck essentially supported by three support points. For example, the three support points may be located at the points of contact with the ground of a pair of spaced apart front wheels, and a third point of contact with the ground may be located at the contact of at least one rear wheel that is at a middle rear position on the forklift truck frame or chassis. Compared to four pivot fork lift trucks, a three pivot forklift truck has similar stability, but more flexibility or maneuverability in steering, especially when turning 360 degrees.
A traditional three pivot forklift truck is driven by dual drive motors, and uses applied hydraulic steering. The hydraulic steering has a pump that is driven by a pump motor to generate hydraulic pressure for the system. The pressure is output to the steering wheel diverter valve. Steering system pressures are determined by the rotational position of an operator steering wheel and are distributed to the horizontal steering master cylinder on a steering bridge. The cylinder on the steering bridge drives directional rotation of the wheels, so as to achieve steering of the forklift truck. However, the existence of the hydraulic steering system pressures causes the steering system to feel heavy or require such effort from an operator that it can easily make an operator tired. In addition, it requires power to maintain the system pressure, which causes large energy losses and consumption. Additionally, a hydraulic steering system has a potential risk for leakage of the hydraulic fluid.
Traditional counterbalanced forklift trucks usually have counterweight blocks inside the forklift truck frame, at the back of truck. Counterweight blocks add to the vehicle weight to offset the same weight relative to the truck's capacity, so as to make the truck be balanced. As such, the counterweight blocks make the truck heavy and reduce the flexibility of the capacity. Traditional forklift trucks usually use a motor that includes a fueled engine or battery to produce power. Forklift trucks with a battery usually locate the battery under the operator's seat, which makes the charging the battery inconvenient and it is not easy to check the charging status, which subjects the batter to less protection and tends to reduce the battery life.